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nielsm posted:Three Notch Road seems to be larger/more important. If that was in Europe, Point Lookout Road would probably have had a yield sign towards Three Notch Road, and Three Notch Road no controlling signs apart from notices that there is a side road. The turn lanes would have been removed, except for turning southwards coming from east (left turn from the larger road.) I think Point Lookout Road has too much traffic to have a layout as uncontrolled such as that. If you pan northwest to the next intersection (Baptist Church Road) the layout is pretty much as you described. In Europe what you would probably have is a roundabout... not that similar junction's don't exist in Europe (though in this case the layout exists due to legacy and money saving, also this isn't quite the same actually but some similar principles apply). For Point Lookout road, its simply a slightly more efficient type of T-intersection with signals without shelling out for grade separation or a roundabout. The main downside I can see is that it it basically an example of having left hand exits on a divided highway for NW-bound, which you always want to avoid if you can, though there are plenty of at-grade intersections along here anyway so I'm guessing traffic isn't too high. The example I posted from the UK removed the nozz fucked around with this message at 13:39 on Oct 11, 2013 |
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Oct 11, 2013 13:21
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Yep, this is what a similar situation looks like in the UK: http://goo.gl/jsj79G It's slightly more complicated because there's another road on the other side, but you get the idea. It's totally common on dual carriageways (i.e. not Motorway standard roads, but still multi-lane and high volume) with small side roads. e: Hi there, A303 buddy.
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Oct 11, 2013 13:28
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Cocoa Crispies posted:The 826/836 shitfest of construction? One of the many reasons I rarely leave the Grove. I get to drive through it twice a day! It's like Russian roulette.
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Oct 11, 2013 13:42
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Oh, thanks! That does makes sense. I just haven't seen that type of configuration anywhere before then and anywhere since. Three Notch Road/Leonardtown Road is basically the main thoroughfare between various communities in southeastern Maryland, along with the Patuxent River Naval Air Station, and Washington D.C. so it gets a fair amount of traffic. It seems the state has been trying to alleviate the congestion around some of the more problematic areas with bypasses (with roundabouts at the ends of the exit/entrance ramps) like this one: http://goo.gl/maps/kXpBC The State Highway Administration helpfully has provided a map of the county and the traffic counts along each road: http://www.marylandroads.com/Traffic_Volume_Maps/stmarys.pdf The intersection in question is in the northern section of the county. Point Lookout looks to get about 8,953 vehicles/day near that intersection and Three Notch gets 29,750 vehicles/day.
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Oct 11, 2013 14:09
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Alakantar posted:I've been reading this thread for the past several months (it's been fascinating!), and I've got two questions. I was driving through Maryland several weeks ago on MD 5/235 and saw several of these strange intersections: http://goo.gl/maps/fM7r8 Ours tend to be a bit simpler than that, and usually non-signalized. Varance fucked around with this message at 02:26 on Oct 12, 2013 |
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Oct 12, 2013 02:21
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Varance posted:FDOT calls those things Turbo T-intersections. They're usually built where a high traffic road meets a non-through low traffic road that sees a significant amount of freight traffic and/or has visibility problems caused by an awkward angle. The basic design allows vehicles to safely orient their vehicle for the turn without having to worry about other vehicles getting in the way. In the example you linked, the turning areas are exaggerated to match the turning profile of a tractor trailer taking a sharp/shallow turn. I think the Green Book calls them high-type intersections. They're great for minimizing conflicts and maximizing speed - not always the best combination for safety, which is why we're steadily replacing them with normal signals here.
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Oct 12, 2013 04:31
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Cichlidae posted:I think the Green Book calls them high-type intersections. They're great for minimizing conflicts and maximizing speed - not always the best combination for safety, which is why we're steadily replacing them with normal signals here. Meanwhile, we have a higher pedestrian fatality rate than Chicago's murder rate. Varance fucked around with this message at 13:48 on Oct 12, 2013 |
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Oct 12, 2013 13:39
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Cichlidae posted:I think the Green Book calls them high-type intersections. They're great for minimizing conflicts and maximizing speed - not always the best combination for safety, which is why we're steadily replacing them with normal signals here. One of those was just built here (hwys 13/101), but with an overpass. It works alot better than the signal it replaced. (I wonder if it has a special name?) quote:Cloverleafs Eh, you learn and you get used to them, especially if they're used for every freeway-freeway interchange.
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Oct 13, 2013 05:02
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Cichlidae, what do you think of Fall River having this stone monument(?) in the middle of MA 81? I drove by it a few days ago and was struck by what a bad idea it seemed.
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Oct 14, 2013 22:39
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It doesn't seem as poorly placed as the Newtown flagpole, so there's that.
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Oct 14, 2013 23:47
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The next phase of the €4.1 billion Schiphol-Amsterdam-Almere project is right around the corner here in the Netherlands, they'll start cutting trees and surveying before the end of the year. There's a bit of a public relations push as well, the national infrastructure authority posted two videos on YouTube, although they're not as professional as the ones done for other projects. Street level: https://www.youtube.com/watch?v=yHHIHJ7RdjY Bird's-eye: https://www.youtube.com/watch?v=A_8jN0wEw_U Both are a 6m 24s watch.
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Oct 15, 2013 00:13
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Airconswitch posted:Cichlidae, what do you think of Fall River having this stone monument(?) in the middle of MA 81? I drove by it a few days ago and was struck by what a bad idea it seemed. Any monument within the clear zone is a very bad idea. It should either be moved or protected with barrier / guiderail. Somehow, though, I doubt any municipality would let the DOT do that, even if it meant killing someone every now and then. Koesj posted:The next phase of the €4.1 billion Schiphol-Amsterdam-Almere project is right around the corner here in the Netherlands, they'll start cutting trees and surveying before the end of the year. There's a bit of a public relations push as well, the national infrastructure authority posted two videos on YouTube, although they're not as professional as the ones done for other projects. That's a massive project! Those overhead lane arrows everywhere - are they used for maintenance and incident management? It seems like a really good idea, though; one life saved would justify just about the entire cost.
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Oct 15, 2013 12:21
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Cichlidae posted:Any monument within the clear zone is a very bad idea. It should either be moved or protected with barrier / guiderail. Somehow, though, I doubt any municipality would let the DOT do that, even if it meant killing someone every now and then. Is this on a fast highway? Over in the UK they've taken to putting things like benches and plants on roads that you should travel slowly down, in an attempt to slow you down even more and stop people overtaking. There's no barriers either. I wouldn't sit in the middle of a loving road, even one with a 20mph limit through a small town centre. gently caress that.
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Oct 15, 2013 15:20
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Cichlidae posted:That's a massive project! Those overhead lane arrows everywhere - are they used for maintenance and incident management? It seems like a really good idea, though; one life saved would justify just about the entire cost. Yup, maintenance and incident management. They're VMS as well:  That's a pic from 1985, the first ones came online in the late seventies. Large parts of the network are covered nowadays: 
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Oct 15, 2013 15:39
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Koesj posted:Yup, maintenance and incident management. They're VMS as well: Turns out there's over 2100 of them so far   Go here if you want to poke around in their mapviewer. All their data is also available as WMS\WFS layers (full list) that you can add to ArcGIS and a bunch of other applications. The DTB and KernGIS layers are the most interesting ones for this thread because they contain all objects on and around the highways.
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Oct 15, 2013 16:56
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Cichlidae posted:Any monument within the clear zone is a very bad idea. It should either be moved or protected with barrier / guiderail. Somehow, though, I doubt any municipality would let the DOT do that, even if it meant killing someone every now and then. A lot of those monuments have a nice short wrought-iron fence around them. But that would just move stuff even closer to the travel lane, and something nice enough for this purpose would probably not be very crash friendly.
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Oct 15, 2013 17:32
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Don't things you can crash into near the sides of the road generally reduce speeds and force people to drive more carefully? I know where I live they're always trying to narrow roads and plant trees or add street parking to help reduce speeds and get people more alert. Is every road supposed to have a 500m field of soft foam around it or something?
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Oct 15, 2013 17:41
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E: Meh, disregard.
Carbon dioxide fucked around with this message at 18:24 on Oct 15, 2013 |
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Oct 15, 2013 17:49
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It doesn't really seem as if the people who need to slow down the most pay attention to those things.
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Oct 15, 2013 17:50
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Baronjutter posted:Don't things you can crash into near the sides of the road generally reduce speeds and force people to drive more carefully? I know where I live they're always trying to narrow roads and plant trees or add street parking to help reduce speeds and get people more alert. Is every road supposed to have a 500m field of soft foam around it or something? Slowing speeds by narrowing the roadway corridor is a thing - but it's primarily intended for low speed roadways. Curbs are not considered an obstacle - and if you were going to plant something in the clear zone, it would hopefully be landscaping or shrubs that aren't considered obstacles, but still give you a feeling like the corridor is cramped. This spot isn't the best example due to the planting of trees within the clear zone (in areas w/o guard rail - the rail is there protecting the side slope), but driving it in person really does make you drive slower than if that flat curve were wide open.
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Oct 15, 2013 18:08
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I guess I don't understand why that monument is a problem but all the lamps and telephone poles and such right by the curb aren't. The little monument seems way farther from the edge of the road than buildings usually are along the street. A building 6' from the curb is ok, a lamp a foot from the cub is ok, a little monument 10' from the curb is a horrible danger. I can't think of a single road that doesn't have essentially a "fence" of very firmly planted objects basically lining the curb or a within 6' of the curb. Everything from utility poles to huge 5'+ thick trees. In fact the city is always trying to add more street trees. Some idiot was doing 100+ on my 30 street a few months ago and crashed his luxury suv into a big old tree. Car was reduced to parts, tree had it's bark scratched up a little and the main concern among residents was to get a specialist out to make sure the tree is ok. If the tree wasn't there the car could have carried on into a building or pedestrian. I know as a pedestrian I love as many solid objects between me and drives. Baronjutter fucked around with this message at 18:23 on Oct 15, 2013 |
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Oct 15, 2013 18:17
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Baronjutter posted:I guess I don't understand why that monument is a problem but all the lamps and telephone poles and such right by the curb aren't. The little monument seems way farther from the edge of the road than buildings usually are along the street. A building 6' from the curb is ok, a lamp a foot from the cub is ok, a little monument 10' from the curb is a horrible danger. Lamps are designed to be "breakaway". The bolts that attach it to the ground are engineered to shear off when they get hit hard enough. The Roadside Design Guide has an exception for trees and utility poles, because it acknowledges that you can't always get them far enough away. You try to, though. And both light poles and utility poles are there to serve a purpose - the monument is decorative, and could be made out of something breakaway and/or moved into a safer spot outside the clear zone. You are less likely to see newly planted trees in the clear zone - and with old trees, it's hard to have the political will to cut down an existing enormous tree just for safety improvements. In some cases you might not win the fight with the environmental agency whose responsibility it is to protect the trees.
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Oct 15, 2013 19:27
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Those are fair points, I just don't always agree with the idea that a roads primary and highest purpose is to move cars as fast and safely as possible. Sometimes what is more dangerous to (bad) drivers increases safety to all other users. Many streets and neighborhoods have been destroyed in the name of speed and safety, and I find big open roads ugly as hell. Put that road in a narrow tree tunnel. The trees protect all other users and make it so the road can't ever expand.     That last one has the trees pretty far from the road though. They actively replace all the trees along the roads too if they ever die or fall down. Sometimes even roads that didn't have trees get new ones because who doesn't like street trees? (other than engineers I guess). I honestly don't have any problem with trees killing the odd speeder or idiot on their phone. Like I'd rather them crash into a tree an die them selves than sail through a break-away barrier and hit an innocent pedestrian. These are all on low speed city streets though, I can see totally different standards applying to a highway. Baronjutter fucked around with this message at 19:48 on Oct 15, 2013 |
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Oct 15, 2013 19:44
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Along the lines of trees next to road slowing drivers down, check out this roundabout. It's not necessarily obvious from the satellite imagery, and Street View isn't working for me, but those trees completely block your view of the roundabout until you are across the crosswalk -- not to mention completely blocking your view of the crosswalk until you're within a couple dozen feet. This certainly has the effect of making me slow down, but doesn't it pretty much negate the point of the roundabout? If you have to slow down to < 5 mph to make sure you can stop in time, why bother having a roundabout and yield sign? Or am I just being too cautious about this?
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Oct 15, 2013 19:51
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I've heard mixed things about the CENTRE of a round-about having a view block, but you should always be able to see around both immediate cornes since that's sort of the loving point.
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Oct 15, 2013 19:54
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Baronjutter posted:Those are fair points, I just don't always agree with the idea that a roads primary and highest purpose is to move cars as fast and safely as possible. Sometimes what is more dangerous to (bad) drivers increases safety to all other users. Many streets and neighborhoods have been destroyed in the name of speed and safety, and I find big open roads ugly as hell. Put that road in a narrow tree tunnel. The trees protect all other users and make it so the road can't ever expand. If you think having trees planted makes it so the road can't ever be expanded, that's really just wishful thinking. It's happened plenty before, it'll happen plenty again. It's extremely odd to say the least to see big open roads put in to truly residential neighborhoods, in fact your typical loopy-doopy suburban roads are often designed exactly so that it would be pointless to come back after it's built and make them an arterial route - they're too indirect and often explicitly feed into what amounts to a closed loop of roads, or a set of roads that might technically form a bypass of existing through routes but would require triple the driving distance and a lot more turns.
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Oct 15, 2013 19:57
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Install Windows posted:If you think having trees planted makes it so the road can't ever be expanded, that's really just wishful thinking. It's happened plenty before, it'll happen plenty again. Here the "street tree lobby" or what ever you call it is way too powerful for that to ever happen. Also the city has a pretty progressive stance on roads. I can't remember the last time they ever expanded a road, but they love removing lanes, widening sidewalks, adding bike lanes, road diets, entire road closures. So here the monument example the problem would be that cars might damage it, so lets remove 2 of the 4 lanes, expand the median into a proper little park, and add some bike lanes and cut the speed limit down a notch. And plant some nice oaks or chestnuts around the perimeter to protect people in the park from the evil cars. Also add a signaled crosswalk leading pedestrians through a pleasant path around the monument.
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Oct 15, 2013 20:04
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Baronjutter posted:Here the "street tree lobby" or what ever you call it is way too powerful for that to ever happen. Also the city has a pretty progressive stance on roads. I can't remember the last time they ever expanded a road, but they love removing lanes, widening sidewalks, adding bike lanes, road diets, entire road closures. So here the monument example the problem would be that cars might damage it, so lets remove 2 of the 4 lanes, expand the median into a proper little park, and add some bike lanes and cut the speed limit down a notch. And plant some nice oaks or chestnuts around the perimeter to protect people in the park from the evil cars. Also add a signaled crosswalk leading pedestrians through a pleasant path around the monument. Put up w-beam guardrail to protect the monument, call it a day 
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Oct 15, 2013 20:12
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Baronjutter posted:Here the "street tree lobby" or what ever you call it is way too powerful for that to ever happen. Also the city has a pretty progressive stance on roads. I can't remember the last time they ever expanded a road, but they love removing lanes, widening sidewalks, adding bike lanes, road diets, entire road closures. So here the monument example the problem would be that cars might damage it, so lets remove 2 of the 4 lanes, expand the median into a proper little park, and add some bike lanes and cut the speed limit down a notch. And plant some nice oaks or chestnuts around the perimeter to protect people in the park from the evil cars. Also add a signaled crosswalk leading pedestrians through a pleasant path around the monument. Well usually the reason a tree lined street won't get expanded is because it's just some random street through a residential area and the municipality isn't going to want to bother with the hassle of buying out the property for expansion - the people living along it aren't going to give up the closest 10 feet of their front yard to the town for free. The cost or problems of tree removal are much less than the cost of acquiring property. It's just extremely strange to have a situation where the trees could ever come into it as an actual cause of not expanding. Random residential street #56 in the grid doesn't usually have a compelling reason to get turned into a surface arterial without also being rezoned to mixed use or commercial usage, the demolishment of most of the existing buildings along it, and so on.
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Oct 15, 2013 20:14
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We've actually got a situation here where a busy arterial IS lined with trees. It's A tight 4 lanes with a centre turning lane only on some portions. It's a nightmare to ride a bike down because drivers then all need to get into the other lane to go around the bike, but surprise, there's someone trying to turn left in the other lane so I guess you're hosed. The street has fairly wide sidewalks and generally a good 5-10' of grass and trees between the road and the sidewalk. All the buildings along it are old apartment buildings with stupidly huge city-mandated setbacks full of nothing but useless lawn. One proposal is to cut down the trees and expand the road to fit bike lanes and turning lanes in a couple of the worst spots. This is VERY unpopular to the point of being politically impossible. Many residents and business owners along the street say the wall of trees is the only buffer between them and the horrible arterial and the area will just end up super ugly without them. The trees make this an absolute impossibility, even on an important arterial. The other proposal is to nab a couple meters of these useless apartment front lawns and build bike lanes/sidewalks protected by the trees sort of Berlin style. People are more supportive of this but acquiring all the property will be an absolute clusterfuck. The third proposal is to turn a jammed 4 lane arterial into a 2 lane but with a consistent turning lane in the center and bike lanes on the sides. This would obviously be the cheapest and thus the most likely to actually happen. Some traffic engineers say the road wouldn't have the needed capacity, but every time I hear engineers and their spread sheets cry doom about this sort of thing the traffic just ends up evaporating, people just choose to drive less or drive elsewhere.
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Oct 15, 2013 20:25
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Well exactly. The real problem there is acquiring the property - the trees only need to be straight cut down and removed if the city isn't able/willing to buy additional property to move them on, or additional property to put improvements on without moving the trees. Even without the trees being there, there would have been issues like losing grassy verges, or moving the sidewalks, or other things of that nature. Taking care of those would also require property acquisition or compromises to those features.
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Oct 15, 2013 20:36
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Devor posted:Put up w-beam guardrail to protect the monument, call it a day Small stretches of guiderail are useless. Unless you have a few hundred uninterrupted feet, it's not going to deflect anyone. As for the clear zone, you can't put fixed objects in it to slow down traffic. That's like hot-gluing smashed beer bottles to the walls around your shower so people will be careful not to slip and fall. Utility poles get a free pass because there is no reasoning with utility companies. So we have sign supports 29' off the road with huge barrier protecting them, meanwhile there's an 8" wood pole on every curb.
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Oct 15, 2013 22:33
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How big is the clear zone, or does it vary based on the type and speed of the road? I've never really seen a road with much or any of a "clear zone" other than highways. There's always a "fence" of trees, utility poles, and other junk basically right along the curb and then the fronts of buildings.
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Oct 16, 2013 04:58
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Baronjutter posted:How big is the clear zone, or does it vary based on the type and speed of the road? I've never really seen a road with much or any of a "clear zone" other than highways. There's always a "fence" of trees, utility poles, and other junk basically right along the curb and then the fronts of buildings. It's up to 30 feet from the edge of the traveled way, and it depends on speed, volume, and slope. There's a table in the Roadside Design Guide. I'd show you, but it costs $216...
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Oct 16, 2013 12:08
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Is it only supposed to be applied to suburban or rural areas or something? I can't imagine 30' sidewalks clear of huge concrete planters, or trees, or little pedestrian railings, street furniture, or any of that poo poo. Even a lot of these benches only 5' or so from the curb are solid concrete or metal bolted to the ground. What's the recommended clear zone for say a 40-50kph 4 lane city street? When I imagine roads actually built to these clear-zone standards all I can see are horrible flat open car-centric wastelands. It just seems like one of those rules that sounds nice in a technical vacuum where the only factor weighed is safety for drivers but has little place in the real world other than a sort of general "would be nice" advisory to be balanced against other needs. Drivers already have far too much space allocated to them, now they want the few scraps of land not totally centered around them to be a massive "clear zone" in case their lovely driving sees them up on the sidewalk?? Like, I can see this clear zone having merit in a rural setting with some road in the middle of nowhere. Make sure to have a shoulder and cut trees back 20-30' from the road, that makes sense. But in an urban context?? No way, those trees, those concrete planters, they're only dangerous to lovely drivers while at the same time safety features against said lovely drivers smashing into pedestrians and buildings. Streets might be marginally safer for drives if all our sidewalks were turned into massive clear zones, but it wouldn't be safer for other users and would make our cities super unpleasant. Am I wrong in thinking there needs to be a balance for the needs of all users as well as the aesthetics of the city?
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Oct 16, 2013 17:31
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up to 30 ft. I'd bet for $216 you get a lot of flexibility and formulas to take into account road speed and location.
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Oct 16, 2013 19:32
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In a local traffic street where you're driving along at 50kph (~30mph), if you're running into the street trees/parked cars you're doing something wrong. On the other hand, in Australia the general speed limit on freeways outside of urban areas is 110kph (~70mph) so there's been some agitation to increase the limit to 130kph (~80mph) "just like they do in Europe". Which'd be fine, if the roads were up to scratch. The issue is, some parts of the major freeway between Melbourne and Sydney look like this: https://www.google.com/maps/preview...NIcvw!2e0&fid=5 (that's one carriageway, with trees close to both verges) Not to mention that there are actually still a lot of at-grade intersections along the freeway for minor rural roads - only town exits/entries and major road intersections tend to get proper interchanges.
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Oct 17, 2013 05:05
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I know this is a few pages back, but couldn't help but notice the picture of the one way frontage road with separate left turn signal. I live in Dallas and have driven through those intersections in Frisco that do that. No point to doing that, and I will explain why. The majority of intersections where the freeway frontage roads intersect a cross street have this sort of epic timing to the signals unlike anything else. Four phases that rotate 90 degrees, each direction goes through both signals at once, but they are staggered with epic timing such that it doesn't feel like you wait there that long. Or to explain. Cross street one direction gets green. In perfect timing when you get to the next signal, it turns advance left + thru green. First signal goes red while frontage road counterclockwise gets green while second signal on cross street still advance left + thru. Green arrow disappears and other cross street direction gets green. Frontage road quickly goes red right in time for the traffic from the other cross street direction to get green arrow.
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Oct 17, 2013 07:02
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Is there some city traffic philosophy that basically says "no protected left turns, and no left turns at all during busy times." We saw a lot of that in San Francisco and it really screwed up the GPS.
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Oct 17, 2013 13:22
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smackfu posted:Is there some city traffic philosophy that basically says "no protected left turns, and no left turns at all during busy times." We saw a lot of that in San Francisco and it really screwed up the GPS. To have a protected left turn phase, you generally need a dedicated left turn lane, which is room that could otherwise be used for shoving more through lanes in. So If you have enough room for sidewalks, parking lanes, and two through lanes in each direction, you just don't have room to make a protected left turn work. Which is why you often end up with permissive lefts, and then when rush hour rolls around you have to prohibit the left turn, because otherwise someone will wait there and block the through lane.
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Oct 17, 2013 13:33
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